Relay system



Sept. 24, 1929. SLEEPER 1,729,405

RELAY SYSTEM Filed April 7, 922 2 Sheets-Sheet 1 4/ 42 3a 2a 2/ 22 J .1 ll L 4L 1; z; E f f f 1 1 W I6 /7 18 1 L A 44 45 46 v A A A /r L a9 -L A I 2 40 B R as 57 i wnmzssss; 'g- INVENTOR Harvey F Sleeper:

Sept. 24, 1929. H. P. SLEEPER 1,729,405

RELAY SYSTEM Filed April 7. 1922 2 Sheets-Sheet 2 i wnmasszs; INVENTOR 4K flail. F jg. 2. Harvey PS/ee oer:

Patented Sept. 24, 1929 HARVEY P. SLEEPER, OF WILKIN'SBURG, PENNSYLVANIA; AssisNoE ire WESTING- HOUSE ELECTRIC 85 -MANUFACTURING VANIA I ."P;

a i f Application filed Apr il :7,

My invention relates to protective systems and particularly tosystems for protecting parallel-connected transmission circuits."

One' object of my invention is to provide a I 5 protective system containing means for "effecti ng the disconnection'of one of "a plurality of parallel-connected transmission C11- vcults upon. the occurrence of a ground thereon.

Another object of my invention is to pro vlde a system, of the above-indicated character, containing .means that shallbe operative upon the'occurrence of a ground upon any one of the feeder conductors, and that shall have an inverse time limit for ground currents lessthan a predetermined value and a definitetime limit for ground 'currents'exceeding the predetermined value.

Anothenobject of my invention is to provide a' system, 'o'f' the above-indicated character, containing means that may selectively control the transmission circuit upon which the groundmay occur. I I

Another object of my invention is'to provide a system, of the above-indicated character, containing means that shall be very sensitively responsive to ground currents of small value to control the disconnection of a faulty circuit.

A further object of my invention is to provide a relay system, of the above-indicated character, that shall operate in re-- sponse to, and that shall be energized from, the ground current only.

In United States Patent No. 1,286,415, issued December 3, 1918 to Forrest E. Ricketts and assigned to the lVestinghouse Electric 8: Manufacturing Company, is disclosed a relay of the induction-disc type embodying an inverse time function in its operation that is obtained, and controlled, by means of a saturable transformer that operates to control the torque developed in the relay.

The saturabletransformer permits a torque to be developed in the relay that is proportional to the value of the current traversing the relay. up to'a predetermined value at which the transformer becomes saturated. When the current traversing the relay exceeds the value at which the transformer beknoWn and which relay may be caused to have and a time-limit feature.

actuate the disc' -tion or the other, depending upon the energization of thewindings", to effect engagem'ent between one 'or another set of contact jmembers for controlling the corresponding COMPANY, A CORPORATION or PENNSYL- sYsrE I 1922. 'Serial No. 550,529.

{comes'satu'rate'd, the torque developed in the relay remains constant, irrespective of increase in the value of current traversing the relay reason ofthe regulating effect of the saturated transformer."

United States Patent {to F. E. Ricketts, '1,594,117,Ju1y'1 7, 1926, and assigned to the 'We'stinghouse Electric & Manufacturing Company, discloses a ditferentially-balanced relay that is instantaneous in itsoperation to dlsconnect one of two feeder circuits to which it'may be connected-when that circuit becomes faulty.

" In practicing my invention, I employ a selective relay, that is similar to that disclosed in the above-mentionedRicketts application, and provide therefor a saturable transforlm er, or torque compensator as it iscommonly is described in the abovementioned Ricketts application, whereby the both a directional The relay is provided with two windings that co-operate,

when properly energized, to member either in one-direccircuits associated therewith. Normally, neither of the windings is energized.-

Upon the occurrence of a ground upon one of the circuit conductors, one of the windings is energized in accordance withthe resulting ground current and the other winding is energized from the secondary winding of the saturable transformer, the primary winding of which is energized by the ground current.

' By means of the saturable transformer, the

currents traversing the two windings are electrically spaced from each other in phase relation and their magnetic efi'ects therefore co-operate to actuate the disc member.

Figure 1 of the accompanying drawings is a diagrammatic view of an electrical circuit containing a protective system operated in accordance with my invention, and

Fig. 2 is a diagrammatic view similar to that shown in Fig. 1, except that individual selective relays are employed for the parallelconnected transmission circuits.

In Fig. 1, a source of electromotive force 10, such as a generator or a transformer, having a grounded neutral, suppliespower to a -bus section '11. Power is transmitted from the bus section 11 to a remotely-disposed bus section through two parallel-connected feeder circuits 13 and 14.

'The'circuit 13 is provided with a circuit interrupter 15 and a plurality of current transformers 16, 17 and 18 that are connected in circuit with the respective conductors thereof. The feeder circuit 14 is similarly providedwith a circuit interrupter 19 and a plurality of current transformers 20, 21 and 22, respectively, that are connected in circuit with the respective conductors of that circuit.

. primary windings 32 and 33, respectively, and asecondary winding 34:.

The relay-element comprises a saturable core member-35 embodying a plurality of pole pieces, upon which are mounted two windings 36 and 37, respectively. The relay element 30 further comprises an induction disc armature member that is adapted to actuate amovable contact member 38 to engage either of two contact members 39 or 40 according to the direction of actuation of the disc member.

The corresponding terminals of the current transformers, that are connected in circuit with mil-responding phase conductors of the two transmission circuits, are connected together by auxiliary circuit conductors 41, 42-and 43. The other terminals of the current transformers 16, 17 and 18 are joined and-connected to one terminal of the winding 32 and, similarly, the other terminals of the transformers 20, 21 and 22 are joined and connected to one terminal of the winding 33.

The other terminals of the windings'32 and 33 are joined and connected to one terminal of the winding 37, the other terminal of which is connected to the neutral point of three relay devices 44, 45 and 46, which are normally employed with the system but do not enter into the particular invention disclosed herein. lVhere such relay devices are not employed, an artificial neutral may be established by three'impedance devices similarly disposed. The secondary winding 34 of the torque compensator 29-is connected in series with the winding 36 of the relay element 30.

her 39.

Upon the occurrence of a ground upon one of the conductors of the transmission circuit 13, as indicated at A, the current transformer 18 will be energized by a ground current in addition to the normal current traversing the circuit. Such ground current will traverse, in addition to the current transformer 18, the winding of the relay device 44, the winding 37 of-the relayelement30-and the winding 32 of the saturable transformer, or torque compensator, 29.

The primary winding 32 of the saturable transformer 29 being energized by the ground current, the secondary winding 34 will be caused to energize the winding 36 of the relay device 30. The current caused to traverse the winding 36 will be considerably, displaced in phase relation from thecurrent traversing the windings 32 and 37, and the magnetic eifects of the currents traversing the two windings 36 and 37 of the relay device 30 will consequently co-operate to actuate the disc member 38 to move the associated contact member to engage the contact mem- The engagement of the contact member 39 by the contact member 38 will complete the circuit of the trip coil25 to actuate the interrupter 15 and thereby disconnect the transmission circuit 13 from the bus sec- 'tion 11.

If-the-ground shouldoccur upon a conductor of the transmission circuit 14, as indicated at B, -a ground currentwouldtraverse .that conductor and energize the secondary transformer winding 20. Current would traverse the secondary transformer winding20, the winding 33 of the saturable transformer, the winding 37 of the relay element-30 and the relay device 44;

Under :such conditions of energization, the windings 36 and 37 will be so relatively energized that the disc member 38 will be controlled to etfect'engagement between the associated contact member and the contact member 40. The trip coil 27 will thereupon be energized to actuate the interrupter 19 to disconnect the transmission circuit 14 from the bus section 11.

It will be seen-that. by means of the relay and the protective system which I have shown, the A necessity of potential transformers may be obviated to obtain selective control of a plurality of pa-rallel-connected transmission circuits. By means of the arrangement shown, the control relay is energized only bya current corresponding to the ground current, and by an auxiliary current established thereby.

If a ground fault should occur on, or beyond, the remotely-disposed bus circuit supplied through the transmission circuits 13 and 14, the ground current would divide between the corresponding conductors of the two circuits. Current .would traverse the current transformers associated with the grounded-phase conductors but such current would not be efiective in operating the relay 30 since the magnetic effects of the two windings 32 and 33 of the saturable transformer' 29 would counterbalance and neutralize each other.

In Fig. 2, I have illustrated individual single-contact relay elements which may be employed for the respective circuits. The windings 36 of both relays would be connected in series with the single winding 34 of the compensator 29 and the windings 37 of both relays would be connected in series. The windings 37 of both relays should be con nected in reverse manner relative to each other to render the relays properly selective. Upon the occurrence of a ground fault on a conductor of either circuit, the proper relay would disconnect the faulty circuit.

It is obvious from a review of the system which I have disclosed, that by means of a protective system containing a relay of the character illustrated, relatively sensitive selective control may be obtained to protect parallel-connected transmission circuits, since the ground current that results from the occurrence of a ground on one of the conductors of the circuits is magnified by means of the two-winding relay, each of which is energized substantially in accordance with the value of the ground current resulting from the faulty condition.

My invention is not limited to a relay of the particular character which I have illustrated or to a system in which a relay device shall be arranged in the manner illustrated, since various modifications may be made both in the relay device and in the system to obtain the same results without departing from the spirit and scope of my invention, as set forth in the appended claims.

I claim as my invention:

1. In an electric distributing system, the combination with a plurality of parallel-connected feeder circuits, of means including a relay connected to said plurality of circuits for disconnecting a circuit rendered faulty by a ground upon one of the conductors thereof comprising means energized in accordance with the product of two magnetic effects varying with the value of the ground current and limiting means for so controlling the energization of said first-mentioned means as to provide said disconnecting means with a definite-minimum time characteristic.

2. In a relay protective system, the combination with a plurality of current trans formers energized by the currents traversing the respective phase conductors of an electric circuit, of a neutral conductor circuit traversed by a current upon the occurrence of a ground upon one of the phase conductors of the circuit and means energized from the neutral conductor circuit comprising a transformer and a relay provided with two wind-= ings, the primary winding of the transformer and one winding of the relay being connected in circuit with the neutral conductor and the secondary winding of the transformer being connected in circuit with the second winding of the relay.

3. A relay protective system, comprising two sets of current transformers connected in star relation, a conductor oining the star or neutral points, a plurality of auxiliary conductors joining the free ends of corresponding transformers of the two sets, two relay windings connected in the neutral-conductor circuit, means connected to the auxiliary conductors for establishing an artificial neutral point and means connected between the junction of the two windings and the artificial neutral and co-operating with one of the windings to control an external circuit.

4r. In a relay system for two parallel-connected feeder circuits, the combination with a set of current transformers for each feeder circuit, of a neutral-circuit conductor connected to the transformers to be traversed by current only upon the occurrence of a ground fault upon either feeder circuit, and an induction relay comprising two windings, means connecting one winding with the neutral-circuit conductor to cause that winding to be directly energized by the ground current and means between the neutral-circuit conductor and the other winding to cause the latter winding to be energized by a cur rent proportional to the ground current and a conducting armature member cooperating with said windings.

5. In an electrical distribution system, the combination with a plurality of parallel-connected feeder circuits and respective interrupters therefor, of selective means includ ing a relay and means for obtaining an inverse time function in its operation for discriminating between the feeder circuits to efi'ect the disconnection of a circuit upon which a ground occurs.

6. In an electrical distribution system, the combination with a plurality of parallelconnected feeder circuits and respective interrupters therefor, of a normally balanced directional relay responsive to an unbalance for effecting the disconnection of a circuit rendered faulty by a ground thereon, by rea son. of which the unbalance occurred, and means whereby the disconnection is effected in accordance with the severity of the fault in an inverse-definite-mininmm period of time.

In testimony whereof, I have hereunto subscribed my name this 31st day of March 1922.

HARVEY P. SLEEPER. 

